scholarly journals Variations of the 238U/235U isotope ratio in metasedimentary rocks and evidence of changes in sedimentation conditions during the Ediacaran period of the Neoproterozoic

2019 ◽  
Vol 484 (4) ◽  
pp. 472-477
Author(s):  
A. V. Chugaev ◽  
I. V. Chernyshev ◽  
A. E. Budyak ◽  
G. V. Mandzhieva ◽  
A. S. Sadasyuk ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Isotope Ratio ◽  
Redox Conditions ◽  
Fold Belt ◽  
Marine Origin ◽  
Metasedimentary Rocks ◽  
Geological Processes ◽  
Terrigenous Rocks ◽  
Icp Ms ◽  
Sedimentation Conditions

The isotopic composition of uranium is a new geochemical indicator that facilitates reconstruction of the redox conditions of geological processes. In this paper the results of study of the 238U/235U isotope ratio in the Neoproterozoic metasedimentary rocks of the Baikal–Patom fold belt (Northern Transbaikalia) were obtained using the MC-ICP-MS method and 233U+236U double spike. The scale of 238U/235U ratio variations (δ238U = –0.37 to –0.11‰) is within the range of (–0.39 to +0.15‰), typical of metasedimentary terrigenous rocks of marine origin. In terms of the δ238U values, uranium of the BPB rocks studied is heavier than seawater uranium (δ238U = –0.41 ± 0.03). There is a correlation between the δ238U value in the rocks and their position in the stratigraphic section. Variations of the 238U/235U ratio in the terrigenous-carbonate sequences of BPB indicate that the sedimentation conditions changed and euxinic conditions were established in the course of evolution of the paleobasin in the Late Ediacarian Period.

Variations of the 238U/235U Isotope Ratio in Metasedimentary Rocks and Evidence of Changes in Sedimentation Conditions during the Ediacarian Period of the Neoproterozoic

2019 ◽  
Vol 484 (2) ◽  
pp. 167-172 ◽  
Author(s):  
A. V. Chugaev ◽  
I. V. Chernyshev ◽  
A. E. Budyak ◽  
G. V. Mandzhieva ◽  
A. S. Sadasyuk ◽  
...  
Keyword(s):  
Isotope Ratio ◽  
Metasedimentary Rocks ◽  
Sedimentation Conditions

scholarly journals Age and sources of the metasedimrntary rocks of the Tokur terrane in the Mongol-Okhotsk fold belt: results of the U–Pb geoсhronological and Lu–Hf isotope studies

2019 ◽  
Vol 486 (4) ◽  
pp. 446-450
Author(s):  
V. A. Zaika ◽  
A. A. Sorokin ◽  
A. P. Sorokin
Keyword(s):  
Detrital Zircons ◽  
Hf Isotope ◽  
Fold Belt ◽  
Metasedimentary Rocks ◽  
The North ◽  
Icp Ms ◽  
North Asia ◽  
Southeastern Margin ◽  
Isotope Studies ◽  
Metamorphic Complexes

This paper presents the results of U–Pb (LA–ICP–MS) and Lu–Hf ­isotope studies of detrital zircons from metasedimentary rocks of the Tokur Terrane. It has been shown that metasedimentary rocks of the Tokur and Ekimchan formations are characterized by similar age peaks of detrital zircons, which indicates a close (or same) age of these formations. The lower age of the sedimentation is determined by the age of the youngest zircons of 326–323 Ma. The upper age boundary is determined of 254–251 Ma, based on the intruded of the Late Permian granitoids. The main sources of zircons in the metasedimentary rocks of the Tokur Terrane are the igneous and metamorphic complexes of the southeast framing of the North Asia Craton. The Tokur Terrane can be considered as a fragment of the Paleozoic accretionary complex, the formation in front of the southeastern margin of the North Asia Craton.

scholarly journals The exotic inim block of the argun continental superterrane of the central asian fold belt: results of U-Th-pb geochronological (LA-ICP-MS) and Sm-Nd isotopic-geochemical studies

2019 ◽  
Vol 484 (6) ◽  
pp. 734-738
Author(s):  
R. O. Ovchinnikov ◽  
A. A. Sorokin ◽  
A. B. Kotov ◽  
E. B. Sal'nikova ◽  
V. P. Kovach ◽  
...  
Keyword(s):  
Continental Crust ◽  
Central Asian Fold Belt ◽  
Fold Belt ◽  
Early Precambrian ◽  
Metasedimentary Rocks ◽  
Tectonic Events ◽  
Central Asian ◽  
Icp Ms ◽  
Archean Crust ◽  
Geochemical Studies

The results of studies indicate that the age of the protoliths of garnet-bearing biotite–sericite–muscovite schists of the Inim Block is <991 Ma, and they are derived from rocks of the Neo-, Meso-, and Paleoproterozoic (as well as Archean) crust. This suggests that the Inim Block is exotic relatively to the Argun Superterrane due to the formation of the protolith of its metasedimentary rocks largely from erosion products of the Early Precambrian continental crust, the presence of which within the Argun Superterrane is not proven. It is not excluded that the Inim Block is a fragment of the Dzhugdzhur–Stanovoi Superterrane implanted in the structure of the Argun Superterrane as a result of Mesozoic tectonic events.

Precise Mo isotope ratio measurements of low-Mo (ng g−1) geological samples using MC-ICP-MS

2016 ◽  
Vol 31 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Jie Liu ◽  
Hanjie Wen ◽  
Yuxu Zhang ◽  
Haifeng Fan ◽  
Chuanwei Zhu
Keyword(s):  
Bias Correction ◽  
Isotope Ratio ◽  
Geological Samples ◽  
Mass Bias ◽  
Geological Processes ◽  
Icp Ms ◽  
Wide Range ◽  
Isotope Ratio Measurements

The double-spike (DS) mass bias correction approach was the method of choice for geological samples with <0.5 μg g−1 Mo; both the double-spike and the sample-standard bracketing (SSB) approaches could be applied for samples with >0.5 μg g−1 Mo. This method provided a wide range of applications for most Mo reservoirs in geological processes.

scholarly journals Age and sources of the Lower Mesozoic metasedimentary rocks of the Un'ja-Bom terrane in the Mongol-Okhotsk fold belt: results of the U–Th–Pb geohronological (LA–ICP–MS) AND Sm–Nd isotope studies

2019 ◽  
Vol 484 (4) ◽  
pp. 455-459
Author(s):  
V. A. Zaika ◽  
A. A. Sorokin ◽  
V. P. Kovach ◽  
A. P. Sorokin ◽  
A. B. Kotov
Keyword(s):  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Fold Belt ◽  
Relative Probability ◽  
Nd Isotope ◽  
Metasedimentary Rocks ◽  
Icp Ms ◽  
Isotope Studies ◽  
Geochemical Studies ◽  
Age Estimates

The results of the U—Th—Pb geochronological studies indicate that in the Un’ja-Bom terrane the youngest peaks on the relative probability curves of ages are 207 and 212 Ma for zircons from the metasiltstone of the Kurnal formation and from the metasiltstone of the Amkan formation. Similar age estimates for the youngest peaks were obtained for the detrital zircons from the metasedimentary rocks of the Tukuringra terrain of the eastern part of the Mongol-Okhotsk belt, which indicates that the Lower Mesozoic flyschoid complexes in the structure of this belt are developed much wider than is currently believed. The results obtained in our U—Th—Pb geochronological and Sm—Nd isotope geochemical studies suggest’s that the sedimentary rocks material was carried to the sedimentation basin mainly from the continental massifs of the Amur superterrane.

Determination of the isotopic composition of sub-ng amounts of Sr in Antarctic snow by multi-collector ICP-mass spectrometry

2017 ◽  
Vol 32 (5) ◽  
pp. 1004-1008 ◽  
Author(s):  
Andrea Bazzano ◽  
Kris Latruwe ◽  
Marco Grotti ◽  
Frank Vanhaecke
Keyword(s):  
Mass Spectrometry ◽  
Isotopic Composition ◽  
Isotope Ratio ◽  
Sr Isotope ◽  
Atmospheric Particulates ◽  
Icp Ms ◽  
Antarctic Snow ◽  
Ancient Times ◽  
Icp Mass Spectrometry

Determination of the87Sr/86Sr isotope ratio in Antarctic snow by multi-collector ICP-MS can provide useful information on the sources of the atmospheric particulates in present and ancient times.

Analysis of Rare Earth Elements in Rock and Mineral Samples by ICP-MS and LA-ICP-MS

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Sven Sindern
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Isotope Ratio ◽  
Ion Source ◽  
Element Determination ◽  
Rock Interaction ◽  
Geological Processes ◽  
Icp Ms ◽  
Ratio Determination

AbstractThe group of the rare earth elements (REEs) serves as valuable indicator of numerous geological processes such as magma formation or fluid–rock interaction. The decay systems of the radioactive REE isotopesThe inductively coupled plasma (ICP) ion source and various types of mass spectrometers (MS) represent the basis to fulfil the analytical requirements of geoscientific studies. Today, ICP-quadrupole MS and ICP-sector field MS (SFMS) with a single detector or multiple ion collection (MC-ICP-MS) are standard instruments for REE analyses in the geosciences. Due to the need for in situ analysis, laser ablation (LA)-ICP-MS has become an important trace element microprobe technique, which is widely applied for determination of REE concentrations and isotope compositions in geoscientific laboratories.The quality of concentration analysis or isotope ratio determination of REEs by ICP-MS and LA-ICP-MS is affected by many parameters. Most significant are interferences caused by polyatomic oxide and hydroxide ion species formed in the plasma as well as fractionation effects leading to non-stoichiometric behaviour during element determination or to biased isotope ratio measurements. Laser-induced fractionation and isobaric interferences have to be considered as additional effects for LA-ICP-MS. As analyte elements and matrix are unseparated, mineral standards matching the matrix of samples are a prerequisite for accurate and precise REE concentration and isotope ratio determination. Application of fs lasers instead of the more common ns lasers in LA-ICP-MS systems turns out to be a significant step to reduce laser-induced fractionation and to overcome effects of sample matrices.

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